/**

  * Back 2 Browser Bytecode Translator

  * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, version 2 of the License.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. Look for COPYING file in the top folder.

  * If not, see http://opensource.org/licenses/GPL-2.0.

  */

 package org.apidesign.bck2brwsr.launcher;

 import java.io.Closeable;

 import java.io.File;

 import java.io.IOException;

 import java.lang.reflect.Constructor;

 /** An abstraction for executing tests in a Bck2Brwsr virtual machine.

  * Either in {@link Launcher#createJavaScript JavaScript engine}, 

  * or in {@link Launcher#createBrowser external browser}.

  * <p>

  * There also are methods to {@link #showDir(java.io.File, java.lang.String) display pages} 

  * in an external browser served by internal HTTP server.

  *

  * @author Jaroslav Tulach <jtulach@netbeans.org>

  */

 public abstract class Launcher {

     Launcher() {

     }

     /** Initializes the launcher. This may mean starting a web browser or

      * initializing execution engine.

      * @throws IOException if something goes wrong

      */

     public abstract void initialize() throws IOException;

     /** Shuts down the launcher.

      * @throws IOException if something goes wrong

      */

     public abstract void shutdown() throws IOException;

     /** Builds an invocation context. The context can later be customized

      * and {@link InvocationContext#invoke() invoked}.

      * 

      * @param clazz the class to execute method from

      * @param method the method to execute

      * @return the context pointing to the selected method

      */

     public InvocationContext createInvocation(Class<?> clazz, String method) {

         return new InvocationContext(this, clazz, method);

     }

     /** Creates launcher that uses internal JavaScript engine (Rhino).

      * @return the launcher

      */

     public static Launcher createJavaScript() {

         try {

             Class<?> c = loadClass("org.apidesign.bck2brwsr.launcher.JSLauncher");

             return (Launcher) c.newInstance();

         } catch (Exception ex) {

             throw new IllegalStateException("Please include org.apidesign.bck2brwsr:launcher.html dependency!", ex);

         }

     }

     /** Creates launcher that is using external browser.

      * 

      * @param cmd <code>null</code> to use <code>java.awt.Desktop</code> to show the launcher

      *    or a string to execute in an external process (with a parameter to the URL)

      * @return launcher executing in external browser.

      */

     public static Launcher createBrowser(String cmd) {

         try {

             Class<?> c = loadClass("org.apidesign.bck2brwsr.launcher.Bck2BrwsrLauncher");

             Constructor<?> cnstr = c.getConstructor(String.class);

             return (Launcher) cnstr.newInstance(cmd);

         } catch (Exception ex) {

             throw new IllegalStateException("Please include org.apidesign.bck2brwsr:launcher.html dependency!", ex);

         }

     }

     /** Starts an HTTP server which provides access to classes and resources

      * available in the <code>classes</code> URL and shows a start page

      * available as {@link ClassLoader#getResource(java.lang.String)} from the

      * provide classloader. Opens a browser with URL showing the start page.

      * 

      * @param classes classloader offering access to classes and resources

      * @param startpage page to show in the browser

      * @return interface that allows one to stop the server

      * @throws IOException if something goes wrong

      */

     public static Closeable showURL(ClassLoader classes, String startpage) throws IOException {

         Launcher l = createBrowser(null);

         l.addClassLoader(classes);

         l.showURL(startpage);

         return (Closeable) l;

     }

     /** Starts an HTTP server which provides access to certain directory.

      * The <code>startpage</code> should be relative location inside the root 

      * directory. Opens a browser with URL showing the start page.

      * 

      * @param directory the root directory on disk

      * @param startpage relative path from the root to the page

      * @exception IOException if something goes wrong.

      */

     public static Closeable showDir(File directory, String startpage) throws IOException {

         Launcher l = createBrowser(null);

         l.showDirectory(directory, startpage);

         return (Closeable) l;

     }

     abstract InvocationContext runMethod(InvocationContext c) throws IOException; 

     private static Class<?> loadClass(String cn) throws ClassNotFoundException {

         return Launcher.class.getClassLoader().loadClass(cn);

     }

     void showDirectory(File directory, String startpage) throws IOException {

         throw new UnsupportedOperationException();

     }

     void showURL(String startpage) throws IOException {

         throw new UnsupportedOperationException();

     }

     void addClassLoader(ClassLoader classes) {

         throw new UnsupportedOperationException();

     }

 }